Reflecting Light

Greetings. I'm fairly new at 3D modeling and rendering, and I had a question that I've been trying to figure out myself with not much success.

Suppose you had a light fixture in a room that was suspended from the ceiling, and this light fixture had a cowling around it. You see this sort of setup often in workshops or factories with high roofs and hanging florescent lights. Naturally, the light wouldn't reach the ceiling directly from the light source because of the cowling, however, once it reflects off of the floor and whatever else is there, it would. I have this realistic situation set up in my drawing, however, on every render higher than "Draft", everything above the level of the cowlings is black.

What are my options to fix this? I'm guessing it would be a tweak to the material properties or the rendering settings, but all my material properties are fairly (probably unrealistically) reflective, and I wouldn't even know where to begin with the rendering settings. I know there is one other option; giving each material it's own self luminescence. I have tried this, but for whatever reason (perhaps my untrained eye), it seems to give an unrealistic result and I would rather avoid it, unless it's a common practice in which to simulate reality, in which case I would ask how to make it look more natural.

Any advice would be greatly appreciated!

Do you have any ambient lighting on?

can you post a pic of your renderings?

I'm not sure if I have ambient lighting on or not. I probably don't, if it's something that needs to be manually set, and isn't part of the default rendering options.

Here are some pics. They are a lower quality rendering, so you can see what I'm talking about. The Draft setting seems to illuminate the entire room, whereas the Low setting (and everything higher) keeps everything above the light level in shadow.

Please forgive the low quality of the drafts and of the work itself. I enjoy working in 3D, but I am poor artistically. In case you're wondering, it's supposed to be a room to house servers, hence the suspended ladder racks.

What type of lights are you using and where are they located in the room?

How many lights do you have in the room?

Have you enabled Global Illumination and Final Gather?

How many Photons are you using?

How many Rays are you using?

Can you post a screenshot of your render settings?

Go into your Autocad Help files and search the index for "Photorealistic Rendering" and read through all the topics available.

Here's a screenshot that should answer a few questions. Sorry about not answering them before, I'll try to be more thorough in the future.

The lights are point lights with a cylindrical shape; I modified the 4' florescent light that comes with AutoCAD, since I didn't want to create a clear cylinder to go around the light object (other renderings will show from eye-level, so the lights will have to exist). I'm still not pleased with the lights. I spent days on them. I didn't want all that extra rendering time for 28 mostly-clear objects, when I could just have the cylindrical shape already in the light object itself, but at the same time, it was a pain to get a cylindrically shaped point light to cast light in all directions. I'm pretty sure it still doesn't cast the light properly, that is to say, from every point on the cylinder, and in three dimensions. I hacked together a photometric web file from scratch to fix it (a point light casts light in the direction, lengthwise, of the cylinder.. I needed it in all directions), but even that was a shot in the dark. No pun intended.

The roof is 16', the lights are at 13', same with the cowlings. Two 4' lights per cowling, 14 cowlings, so 28 lights total. I didn't mess with the candle power, because I have no idea what the numbers mean, and I figured AutoCAD did. The screenshot shows the room with the roof removed.

I've tinkered with the render settings, but because of my lack of experience, I really don't know what does what. You can ask me how many Rays and Photons I have, I can look at a list and give you a number. I won't really know what it all means.

My screen wasn't large enough to take a screenshot of all the render settings, but I'm pretty sure the menus I minimized are inconsequential to the lighting. If I'm wrong in that assumption, let me know and I'll take another screenshot.

Sorry about the readability of the screenshot.. I'm at work, so I can't access a Photobucket account to get a larger image, and the forum shrinks it fairly dramatically.